Accepted for/Published in: JMIR Formative Research
Date Submitted: Mar 9, 2023
Open Peer Review Period: Mar 9, 2023 - May 4, 2023
Date Accepted: Oct 29, 2023
(closed for review but you can still tweet)
Warning: This is an author submission that is not peer-reviewed or edited. Preprints - unless they show as "accepted" - should not be relied on to guide clinical practice or health-related behavior and should not be reported in news media as established information.
Validation of A Bluetooth-enabled Device for Real-time Detection of Sitting, Standing and Walking
ABSTRACT
Background:
Despite their popularity, many existing physical activity devices do not provide real-time data to measure sedentary and standing time, therefore they cannot be used for just-in-time adaptive interventions to interrupt prolonged sitting.
Objective:
This study assessed the criterion and convergent validity of a Bluetooth-enabled prototype activity tracker called Sedentary behaviOR Detector (SORD) that will be used for real-time and adaptive interventions.
Methods:
Fifteen healthy adults wore SORD and activPAL devices on their thighs while engaging in activities (lying, reclining, sitting, standing, and walking). Direct observation was facilitated with cameras. Algorithms were constructed using Python Programming Language. The Bland-Altman method was used to assess the level of agreement.
Results:
One model generated a low level of bias and high precision for SORD. In this model, accuracy, sensitivity and specificity were all above 0.95 for detecting sitting+ reclining, standing and walking. Bland-Altman results showed that mean biases between SORD and direct observation were 0.3% for sitting+reclining (LoA = -0.3% to 0.9%), 1.19% for standing (LoA = -1.05% to 3.42%), and -4.71% for walking (LoA = -9.26% to -0.16%). Mean biases between SORD and activPAL were -3.45% for sitting+reclining (LoA = -11.59 % to 4.68%), 7.45% for standing (LoA = -5.04% to 19.95%) and -5.40% for walking (LoA = -11.44% to 0.64%).
Conclusions:
Results indicate that SORD is a valid device to facilitate future just-in-time adaptive interventions to reduce sedentary behaviour.
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